7. Lymphatics
Lymphatic drainage of the upper limb is via series of deep and superficial channels that ultimately drain into the axillary lymph nodes. Lymph from the hand and forearm drain from lymphatic plexuses via superficial channels that accompany the basilic and cephalic veins to a series of nodes around the elbow: * superficial and deep cubital lymph nodes * epi/supratrochlear lymph node(s) ** one-to-five nodes lying medial to the brachial vein, just superior to the medial epicondyle of the humerus There are also deep channels that accompany the arteries and drain via the occasional deep lymph node accompanying arteries in the forearm to the axillary nodes. Lymph then drains up the arm, passing through a few deep brachial lymph nodes and deltopectoral lymph node(s) with the cephalic vein at the deltopectoral groove, before draining into: * infraclavicular lymph nodes - predominantly lateral upper limb and lateral two digits * axillary lymph nodes - predominantly medial upper limb and medial three digits Axillary lymph nodes (LN) are in the axilla and receive lymph from vessels that drain the arm, the walls of the thorax, the breast and the upper walls of the abdomen. Anatomically it is divided into 6 groups: # Anterior (pectoral) group: Lying along the lower border of the pectoralis minor behind the pectoralis major, these nodes receive lymph vessels from the lateral quadrants of the breast and superficial vessels from the anterolateral abdominal wall above the level of the umbilicus. # Posterior (subscapular) group: Lying in front of the subscapularis muscle, these nodes receive superficial lymph vessels from the back, down as far as the level of the iliac crests. # Lateral group: Lying along the medial side of the axillary vein, these nodes receive most of the lymph vessels of the upper limb (except those superficial vessels draining the lateral side—see infraclavicular nodes, below). # Central group: Lying in the center of the axilla in the axillary fat, these nodes receive lymph from the above three groups. # Infraclavicular (deltopectoral) group: These nodes are not strictly axillary nodes because they are located outside the axilla. They lie in the groove between the deltoid and pectoralis major muscles and receive superficial lymph vessels from the lateral side of the hand, forearm, and arm. # Apical group: Lying at the apex of the axilla at the lateral border of the 1st rib, these nodes receive the efferent lymph vessels from all the other axillary nodes. The apical nodes drain into the subclavian lymph trunk. On the left side, this trunk drains into the thoracic duct; on the right side, it drains into the right lymphatic duct. Alternatively, the lymph trunks may drain directly into one of the large veins at the root of the neck.2 Surgical levels There are three levels of axillary lymph nodes: * level I - bottom level, below the lower edge of the pectoralis minor muscle * level II - lies underneath/posterior the pectoralis minor muscle * level III - above/medial the pectoralis minor muscle The lymphatic drainage of the breast is of great importance in the spread of carcinoma and about three quarters of it is to the axillary nodes. Lymphatic pathways Lymphatics pass around the edge of the pectoralis major and reach the pectoral group of axillary nodes. Routes through or between the pectoral muscles may lead directly to the apical nodes of the axilla. Lymphatics follow the blood vessels through the pectoralis major and enter the parasternal (internal thoracic) nodes. Connections may lead across the median plane and hence to the contralateral breast. Lymphatics may reach the sheath of the rectus abdominis and the subperitoneal and subhepatic plexuses. There is a free communication between nodes below and above the clavicle and between the axillary and cervical nodes.